FIG. 1 illustrates an IC chip package according to the prior art. The package 10 comprises generally a substrate 11, a chip 12, and a cover 13. The substrate 11 has a top-open receiving chamber 14 and a certain number of conductive pads 16 arranged in predetermined pattern at the bottom of the receiving chamber 14. The chip 12 is adhered to the central portion of the bottom of the receiving chamber 14, and electrically connected to the conductive pads 16 by bonding wires 17. The cover 13 closes the open side of the substrate 11 to protect the chip 12 against external impact or pollutant. The cover 13 shall be made of transparent material in case the chip 12 is an image sensor such as charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS). FIG. 2 shows another design of IC chip package 20 according to the prior art. This design is similar to the IC chip package 10 shown in FIG. 1.
In the aforesaid package 10, the bottom of the receiving chamber 14 must receive the chip 12 and the conductive pads 16 of the substrate 11, and sufficient space should be provided between the chip 12 and the wall of the receiving chamber 14 for the movement of the wire bonding tool, and therefore, the area of the bottom of the receiving chamber 14 must be greater than the chip. Due to the aforesaid reasons, this package does not meet the requirements for light, thin, small, and short electronic products.
Further, since the substrate 11 is generally made of reinforced plastic or ceramic printed circuit board, it is complicated to process the receiving chamber in the substrate.